Feasibility Study of the Replacement/Rehabilitation of a 72-in. Force Main: Fid-Bau Portal

Feasibility Study of the Replacement/Rehabilitation of a 72-in. Force Main

Lovett, Rodney (Rod) / Vieira, Ricardo

The prestressed concrete cylinder pipe (PCCP) North District Wastewater Treatment System 72-in. Interceptor N-9 Force Main (FM), approximately five miles long, conveys wastewater along NW 159th Street to the MD-WASD Northwest District Wastewater Treatment facility. The 72-in. embedded PCCP portion of the pipeline was originally constructed in the late 1970s under Contract S-168. On June 18th, 2010, a portion of the 72-in. PCCP force main experienced a catastrophic failure just west of Northwest 17th Avenue. The corresponding failed pipe, along with an adjacent pipe segment, were removed and replaced at that time. The existing 72-in. FM is located under streets in a heavily populated single family residential area along NE 159 Street between NE 2nd Avenue and NE 10th Avenue and within a high-density residential multifamily area alongside the Biscayne Drainage Canal (C-8), including the Evangel Church International (Evangel Temple of Miami), the Christ Community Church (First Alliance Church of Miami), and Oak Grove Elementary. The project site is located within the City of North Miami Beach, Miami-Dade County, and the City of Miami Gardens. The area in the following limits falls under the City of North Miami Beach: from NE 10th Avenue along NE 159th Street to NE 8th Avenue. Miami-Dade County falls under NE 8th Avenue, along NE/NW 159th Street to the intersection of NW 6th Avenue, along NW 6th Avenue from NW 159th Street to Biscayne Canal (C-8), and along the northern bank of Biscayne Canal (C-8) to NW 155th Drive. The rest of the project site falls under the City of Miami Gardens. A design-build criteria package was proposed for the replacement/rehabilitation of a 72-in. sanitary sewage FM along Northwest/Northeast 159th Street between Northwest 17th Avenue and Northeast 10th Avenue. This rehabilitation/replacement analysis and feasibility study detail the findings of investigations and alternative analyses to provide recommendations for a proposed FM rehabilitation/replacement. The key decisions are to determine whether to rehabilitate or replace (via trenchless or open-cut construction methods) and which of the commercially available rehabilitation methods are suitable for this particular application Open-cut replacement has been the standard practice in the past, but its preferential use over trenchless techniques has been significantly diminished in the past two decades—particularly in the wastewater sector. Awareness of the indirect and social costs associated with utility work in congested urban areas has encouraged the use of full costing approaches in the selection between open-cut replacement and trenchless rehabilitation or replacement methods. The selection of the trenchless rehabilitation approach involved a selection process followed by a more detailed evaluation of the technologies. We excluded some technologies that were obviously not suitable for this application. The remaining technologies may be suitable but have different cost, risk, setup area requirements, life cycle performance, compatible materials, and environmental impacts. Specifying a single technology in this feasibility study may have a negative impact on the competitiveness of bids received. Ideally, a level playing field is created when bidders can propose one of several suitable technologies, so that a fair competition is created with similar performance characteristics specified for each technology.